1. Field of the Invention
This invention relates to supporting apparatus for tube bundles in heat exchangers, and more particularly, to a support for the U-bend tube portion of such tube bundles.
2. Description of the Prior Art
In large heat exchangers, unsupported heat exchanger tubes may be subject to vibrations induced by fluid flowing over the tubes on the outside thereof. This can result in undesired vibration and noise in the heat exchanger. Also, vibration can cause collision and resulting damage to the tubes. To solve this problem, various tube supports have been designed for supporting the tubes to prevent such vibration. The problem with such supports is that they must be carefully designed to avoid obstruction of fluid flow which can result in reduced heat transfer. Several devices have been developed which adequately support the longitudinal tubes in the heat exchanger, but support for the U-bend tube portion is more difficult. Thus, while support of the longitudinal portions is important, vibration can still occur as a result of fluid flow over unsupported U-bend portions.
In U.S. Pat. No. 4,429,739 to Gentry et al., assigned to the assignee of the present invention, one or more V-shaped spacers are placed between adjacent tube panels. While this helps prevent some vibration, it is not totally adequate because the tubes are not supported on all sides. In this apparatus, vertical and horizontal support strips are positioned between the longitudinally extending straight tubes. Rods are positioned in grooves in the strips for additional support of the tubes. Such a support system is essentially the same as disclosed herein for the first and second passes of the longitudinally extending tubes.
In a steam generator design of Combustion Engineering, Inc., vertical and horizontal strips are shown to provide support for the U-bend region of heat exchanger tubes, and is easily adapted to the apparatus shown in U.S. Pat. No. 4,429,739 to Gentry et al. However, such a system does not provide the complete and rigid support of every tube as in the present invention.
U.S. Pat. No. 3,545,537 to Hill, Jr., discloses vertical plates between layers of tubes. Horizontal members fit in slots in the vertical plates and have staggered, curved recesses for supporting horizontal portions of the U-bend tubing. The apparatus is adapted to allow for expansion of the tubing. One problem with such a system is the large area of contact of the support with the tubes which can result in a reduction in heat transfer. The support of the present invention contacts the tubes at a single point or at most a single longitudinal line therealong.